Translation of abstract (English)

This work there investigates the relation between solar activity and climate variation on decadal to multi-centennial scales in the Holocene. The isotope 14C is produced under the influence of the solar wind and was therefore used as proxy for the solar variability. The production of 14C was calculated from the atmospheric 14C activity D14C using an Oeschger-Siegenthaler-type box-diffusion model of the carbon cycle [Oeschger, 1975]. D14C is based on absolutely dated tree-rings and can therefore used as proxy for climate changes. In order to investigate the causes of atmospheric 14C changes we have made model experiments, varying diffusive deep-ocean ventilation, air-sea gas exchange rate and 14C production. For three intervals of low solar activity D14C maxima), centered at 2800 BC, 800 BC and 6200 BC (8K-Event), respectively, the tree-ring parameters (derived from the ring widths) were correlated with the 14C production. The investigations were done on riverine oaks of Rhine, Danube and Main. Furthermore the atmospheric 14C was spectrally analysed with various methods (Singular Spectrum Analysis, Maximum Entropy Method, Multi Taper Method, Digital Filters (IIR) and Wavelets) to obtain solar variability periods. The tree-ring parameters indicate that in these intervals the precipitation increased and the temperature decreased during solar minima, pointing to a role of solar forcing of climate variability. The Model experiments could only explain instances of an observed decreases of D14C by about 10 ‰ over 10-15 years with an unrealistically high increase of the ocean circulation by a factor of 2, the gas exchange rate by a factor of 1.5 or a more realistically decrease of 25 % for the 14C production.